The present invention relates to coated abrasive articles and to methods of making and using the same.
In general, coated abrasive articles have abrasive particles secured to a backing. More typically, coated abrasive articles comprise a backing having two major opposed surfaces and an abrasive layer secured to a major surface. The abrasive layer is typically comprised of abrasive particles and a binder, wherein the binder serves to secure the abrasive particles to the backing.
One common type of coated abrasive article has an abrasive layer which comprises a make layer, a size layer, and abrasive particles. In making such a coated abrasive article, a make layer comprising a first binder precursor is applied to a major surface of the backing. Abrasive particles are then at least partially embedded into the make layer (e.g., by electrostatic coating), and the first binder precursor is cured (i.e., crosslinked) to secure the particles to the make layer. A size layer comprising a second binder precursor is then applied over the make layer and abrasive particles, followed by curing of the binder precursors.
Another common type of coated abrasive article comprises an abrasive layer secured to a major surface of a backing, wherein the abrasive layer is provided by applying a slurry comprised of binder precursor and abrasive particles onto a major surface of a backing, and then curing the binder precursor.
Optionally, coated abrasive articles may further comprise, for example, a backsize layer (i.e., a coating on the major surface of the backing opposite the major surface having the abrasive layer), a presize layer or a tie layer (i.e., a coating between the abrasive layer and the major surface to which the abrasive layer is secured), and/or a saturant which coats both major surfaces of the backing. In another aspect, coated abrasive articles may further comprise a supersize layer covering the abrasive layer. The supersize layer typically includes grinding aids and/or anti-loading materials.
Typically, binder precursors include one or more catalyst(s), initiator(s) and/or curing agent(s) (i.e., collectively referred to as curative) that facilitates curing of the binder precursor by thermal and/or radiation curing methods. The degree of cure of binder precursor (and resulting abrasive properties of the coated abrasive article) typically depends, in part, on the composition of the curative. Generally, radiation curing methods provide rapid curing of binder precursors, but are inhibited by opaque materials such as abrasive particles and/or fillers that block incident radiation (e.g., by shadowing). Binder precursors in make, size, and/or slurry layers of the abrasive layer, and optionally in supersize, backsize, presize, and/or tie layers, and/or saturant are prone to such shadowing. Thermal methods for curing binder precursors are generally not inhibited by shadowing, but are typically slower than radiation curing methods.
A variety of abrasive properties may be associated with coated abrasive articles. One important abrasive property is xe2x80x9cstictionxe2x80x9d. Stiction refers to the force necessary to slide the coated abrasive article against a workpiece during use. Many users of coated abrasive articles consider high stiction aesthetically desirable, associating high stiction with other desirable abrasive performance parameters (e.g., high rate of cut).
There continues to be a need for binder precursors that are useful for making coated abrasive articles, that cure rapidly in the presence of shadowing, have acceptable pot life, and result in coated abrasive articles having improved abrasive properties such as stiction.
In one aspect, the present invention provides a coated abrasive article comprising:
a backing having a major surface;
an abrasive layer secured to at least a portion of the major surface, the abrasive layer comprising a binder and abrasive particles; and
reaction product of components comprising:
polyfunctional acrylate;
polyfunctional cationically polymerizable material; and
ternary curative,
wherein, optionally, the binder comprises at least a portion of the reaction product.
In another aspect, the present invention provides a method for making a coated abrasive article comprising:
providing a backing having a major surface;
applying a make layer comprising a first binder precursor onto at least a portion of the major surface of the backing;
at least partially embedding a plurality of abrasive particles into the make layer;
curing the first binder precursor;
applying a size layer comprising a second binder precursor onto at least a portion of the make layer and plurality of abrasive particles; and
curing the second binder precursor to provide a coated abrasive article,
wherein said method includes incorporating a reaction product of components comprising:
polyfunctional acrylate;
polyfunctional cationically polymerizable material; and
ternary curative,
into said coated abrasive article, and wherein, optionally, at least one of the first or second binder comprises at least a portion of the reaction product.
In another aspect, the present invention provides a method for making a coated abrasive article comprising:
providing a backing having a major surface;
applying a slurry comprising a binder precursor and abrasive particles onto at least a portion of the major surface of the backing; and
curing the binder precursor to provide a coated abrasive article,
wherein said method includes incorporating a reaction product of components comprising:
polyfunctional acrylate;
polyfunctional cationically polymerizable material; and
ternary curative,
into said coated abrasive article, and wherein, optionally, the cured binder precursor comprises at least a portion of the reaction product.
In another aspect, the present invention provides a method of abrading a workpiece comprising:
providing a coated abrasive article according to the present invention;
frictionally contacting at least a portion of the abrasive layer with at least a portion of the surface of the workpiece; and
moving at least one of the coated abrasive article or the workpiece relative to the other to abrade at least a portion of the surface.
Coated abrasive articles according to the present invention are conveniently prepared and typically exhibit one or more improved abrasive properties (e.g., stiction).
As used herein:
xe2x80x9cacrylatexe2x80x9d includes both acrylate and methacrylate;
xe2x80x9cacryloxyxe2x80x9d includes both acryloxy and methacryloxy;
xe2x80x9cactinic radiationxe2x80x9d means particulate and non-particulate radiation and includes electron beam radiation as well as electromagnetic radiation having at least one wavelength in the range of from about 200 nanometers (nm) to about 700 nm;
xe2x80x9caverage acrylate functionalityxe2x80x9d refers to the average number of acryloxy groups per molecule; it is determined for a specified material by dividing the total number of acryloxy groups by the total number of molecules having acryloxy groups;
xe2x80x9caverage cationically polymerizable group functionalityxe2x80x9d refers to the average number of cationically polymerizable groups per molecule; it is determined for a specified material by dividing the total number of cationically polymerizable groups by the total number of molecules having cationically polymerizable groups;
xe2x80x9cbireactive compoundsxe2x80x9d are those which contain at least one ethylenically-unsaturated group and at least one 1,2-epoxide group;
xe2x80x9ccrosslinkedxe2x80x9d means having polymeric sections that are interconnected through chemical bonds (i.e., interchain links) to form a three-dimensional molecular network;
xe2x80x9cepoxy resinxe2x80x9d refers to a material containing molecules having at least one epoxy group;
xe2x80x9cepoxy groupxe2x80x9d refers to an oxiranyl group;
xe2x80x9coligomerxe2x80x9d refers to a polymer molecule having 2 to 10 repeating units (e.g., dimer, trimer, tetramer, and so forth) having an inherent capability of forming chemical bonds with the same or other oligomers in such manner that longer polymeric chains can be formed therefrom;
xe2x80x9cphotoinitiatorxe2x80x9d refers to a substance, which, if exposed to electromagnetic radiation having at least one wavelength in the range of from about 200 nm to about 700 nm, forms an initiator for free radical polymerization;
xe2x80x9cpolyfunctional acrylatexe2x80x9d refers to a material having an average acrylate functionality of at least 2;
xe2x80x9cternary curativexe2x80x9d refers to a combination of components comprising:
free radical photoinitiator;
triarylsulfonium salt having the formula 
wherein R1, R2 and R3 independently represent an, optionally substituted, aromatic group having from about 4 to about 20 carbon atoms, and Yxe2x88x92 represents a non-interfering anion; and
quaternary ammonium salt having the formula 
wherein Xxe2x88x92 is a non-interfering anion.